Dating back to the late 1890's Marshall Mattress of Toronto, Canada, developed and patented in 1900 a pocket spring mattress. The pocketed springs in the mattress, which have become more and more popular since the advent of the Marshall Mattress are designed to flex individually of one another and as such have extremely appealing flex properties. Accordingly, many years later, other companies in addition to Marshall make pocket spring mattresses.
Most mattresses, are provided with a stiffened edge recovery region by adding stiffening components which are not part of the inner spring core.
The main sleep area is reinforced by the stiffer edge region. The stiffer edge region does not have anything surrounding it and therefore must rely on its own reinforced characteristics so that it will not break down over time from people sitting on the edge of the mattress.
The standard method of reinforcing the edge area of a mattress is to rely primarily on edge wires in various configurations and add on components, as shown for example in U.S. Pat. No. 4,462,129, issued Jul. 31, 1994 to Brannock and assigned to Simmons U.S.A. In fact, in U.S. Pat. No. 4,462,129, multiple edge wires are provided in the edge region of the mattress.
In as much as conventional edge wires contribute to, but not fully satisfy the intended reinforcement of the edge region of a mattress, these same edge wires also result in some disadvantages in the mattress construction. For example, they produce an edge region which is much stiffer than and uncomfortable relative to the main sleep area in the mattress without necessarily fulfilling full edge recovery. This therefore decreases the constant usable sleep surface area of the mattress.
In addition, hard edge wires eliminate the possibility of folding the mattress which often becomes necessary when trying to get the mattress through a small access area. Furthermore, conventional non-foldable mattresses with edge wires cannot be used for the new leisure style folding beds or for multi-position hospital beds and the like.